107 lines
3.5 KiB
Markdown
107 lines
3.5 KiB
Markdown
# crc
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[](https://www.gittip.com/alexgorbatchev/)
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[](https://david-dm.org/alexgorbatchev/node-crc)
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[](https://david-dm.org/alexgorbatchev/node-crc?type=dev)
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[](https://travis-ci.org/alexgorbatchev/node-crc)
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[](https://npmjs.org/package/crc)
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Module for calculating Cyclic Redundancy Check (CRC) for Node.js and the Browser.
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# Important: Node >= 6.3.0 < 6.9.2
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There's was a bug in Node [#9342](https://github.com/nodejs/node/issues/9342) that affected CRC calculation if `Buffer.split()` is used (see issue discussion for details). This affected all version starting from `6.3.0` up to but not including `6.9.2`. The patch [#9341](https://github.com/nodejs/node/pull/9341) was released in `6.9.2`. If you are upgrading and seeing odd CRC calculation mismatches, this might be the reason.
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## Features
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* Full test suite comparing values against reference `pycrc` implementation.
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* Pure JavaScript implementation, no dependencies.
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* Provides CRC tables for optimized calculations.
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* Provides support for the following CRC algorithms:
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* CRC1 `crc.crc1(…)`
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* CRC8 `crc.crc8(…)`
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* CRC8 1-Wire `crc.crc81wire(…)`
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* CRC16 `crc.crc16(…)`
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* CRC16 CCITT `crc.crc16ccitt(…)`
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* CRC16 Modbus `crc.crc16modbus(…)`
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* CRC16 Kermit `crc.crc16kermit(…)`
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* CRC16 XModem `crc.crc16xmodem(…)`
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* CRC24 `crc.crc24(…)`
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* CRC32 `crc.crc32(…)`
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## Installation
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```
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npm install crc
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```
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## Usage
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Calculate a CRC32:
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```js
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var crc = require('crc');
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crc.crc32('hello').toString(16);
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// "3610a686"
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```
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Calculate a CRC32 of a file:
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```js
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crc.crc32(fs.readFileSync('README.md', 'utf8')).toString(16);
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// "127ad531"
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```
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Or using a `Buffer`:
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```js
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crc.crc32(fs.readFileSync('README.md')).toString(16);
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// "127ad531"
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```
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Incrementally calculate a CRC32:
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```js
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value = crc.crc32('one');
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value = crc.crc32('two', value);
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value = crc.crc32('three', value);
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value.toString(16);
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// "9e1c092"
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```
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## Running tests
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```
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npm test
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```
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## Thanks!
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[pycrc](http://www.tty1.net/pycrc/) library is which the source of all of the CRC tables.
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# License
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The MIT License (MIT)
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Copyright (c) 2014 Alex Gorbatchev
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated documentation files (the "Software"), to deal
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in the Software without restriction, including without limitation the rights
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to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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copies of the Software, and to permit persons to whom the Software is
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furnished to do so, subject to the following conditions:
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The above copyright notice and this permission notice shall be included in
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all copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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THE SOFTWARE.
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